Degradable, amorphous, fluorochemical acrylate polymers

ABSTRACT

Described is a compound having at least one acrylate monomer, said monomer including at least one pendant group of the structure —O—CH(R f )(R f ′), wherein R f  is a straight chain or branched perfluoroalkyl group with five or less carbon atoms, and R f ′ is a branched perfluoroalkyl group with three to five carbon atoms; and a method of reducing the surface tension of a liquid by adding a compound of the invention to the liquid. Also described is a composition that includes a compound of the invention in an aqueous solution or dispersion; a method of treating a substrate to render it oil-and/or water-repellent that includes treating a substrate with a composition of the invention; a method of coating an electrical device that includes applying a composition of the invention; a method of coating optical fibers that includes applying a composition of the invention; and an article that includes a substrate treated with a composition of the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. provisional applicationSerial No. 60/226,235, filed Aug. 18, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates to a novel class of degradable,amorphous fluorochemical acrylate monomers, oligomers, and/or polymerscontaining pendant branched fluoroalkyl groups that may exhibit lowsurface energy and improved environmental compatibility.

BACKGROUND OF THE INVENTION

[0003] In the art of repellent treatments for substrates,fluorochemicals have found extensive use for nearly half a century aslow surface energy materials for imparting repellency to a variety ofsubstrates. For an overview of fluorochemical repellents, see MasonHayek, Waterproofing and Water/Oil Repellency, 24 Kirk-OthmerEncyclopedia Of Chemical Technology 448-455, 460-462, 3rd ed. (1979).

[0004] The treatment of fibrous substrates (e.g., carpets, fabrics,leather, nonwovens and paper) with fluorochemicals to render themrepellent to water and oil-based stains and resistant to dry soil hasbeen well documented in the art. Successfully treated with thesefluorochemical repellents, such fibrous substrates resist thediscoloration that results from normal staining and soiling and thusretain their original aesthetic appeal. A wide variety of suchfluorochemical repellents are known and described in the art. Among themare the fluorochemical acrylate polymers disclosed in U.S. Pat. No.3,341,497 (Sherman et al.) and U.S. Pat. No. 3,462,296 (Raynolds etal.), fluorochemical carbodiimides disclosed in U.S. Pat. No. 3,896,251(Landucci), fluorochemical esters disclosed in U.S. Pat. Nos. 3,923,715(Dettre), 4,029,585 (Dettre), and 4,264,484 (Patel) and fluorochemicalurethanes and ureas disclosed in U.S. Pat. Nos. 3,398,182 (Guenthner etal.), 4,001,305 (Dear et al.), 4,792,354 (Matsuo et al.) and 5,410,073(Kirchner). Commercial fluorochemical repellents of these various typesare widely available and are sold, for example, under the SCOTCHGARD andTEFLON trademarks.

[0005] Also important is the treatment of hard surface substrates, suchas masonry, stone and glass, with repellents to retard the discolorationof the masonry or stone from exposure to water- and oil-based stains anddeterioration from spalling and efflorescence. Fluorochemical repellentsfor masonry and stone are known. U.S. Pat. No. 5,274,159 (Pellerite etal.) describes certain water-soluble or dispersiblefluorocarbylalkoxysilane surfactants that may be cured onto a masonrysurface. U.S. Pat. No. 6,037,429 (Linert et al.) discloses water-solubletreatments for masonry and stone containing fluorochemical polymershaving pendent fluoroaliphatic, carboxyl, (poly)oxyalkylene and optionalsilyl groups.

[0006] In addition to being useful as repellents, fluorochemicalpolymers have found use as low refractive index coatings for glassoptical fibers to help retain the light in the fiber. U.S. Pat No.5,223,593 (McAllister et al.) describes optical fiber coatings made fromhomopolymers of 1,1-dihydroperfluorocyclohexylmethyl methacrylate.

[0007] Particularly useful as repellents are fluorochemicals containinglong chain perfluoroalkyl moieties (i.e., C₆F₁₃— to C₁₂F₂₅—), as suchmoieties impart very low surface energy to the substrate surface andthus provide the treated substrate with excellent water and oilrepellency. (See, for example, H. C. Fielding, “Organofluorine Compoundsand Their Applications,” R. E. Banks, Ed., Society of Chemical Industry,p. 214 (1979).) Especially preferred from both cost and performancestandpoints are fluorochemical repellents containing primarilystraight-chain perfluorooctyl (C₈F₁₇—) moieties. It is thought, but notrelied upon that such repellents (those containing perfluorooctylmoieties) impart a high degree of repellency to a treated substratebecause the perfluoroalkyl groups align to form an ordered, low energy,liquid crystalline-like structure at the substrate surface. This liquidcrystalline-like structure, is normally formed by heating the substratetreated with a polymer containing perfluorooctyl moieties, to anelevated temperature, e.g., from about 100° C. to about 150° C., toproperly orient the perfluoroalkyl chains.

[0008] However, perfluorooctyl group-containing polymers can ultimatelydegrade to form functional perfluorooctyl-containing compounds. It hasbeen reported that certain functional perfluorooctyl-containingcompounds may tend to bio-accumulate in living organisms. This tendencyhas been cited as a potential concern with regard to some fluorochemicalcompounds. For example, see U.S. Pat. No. 5,688,884 (Baker et al.).

[0009] As a result, there is a desire for new fluorine-containingcompounds that can effectively provide water- and oil-repellentproperties and can be eliminated more effectively from the body (boththe polymer/oligomer and its degradation products). One approach hasbeen to replace the C₆F₁₃— to C₁₂F₂₅— perfluoroalkyl moieties in thecompound with shorter chain analogues (i.e., C₃—C₅ moieties). Forexample, U.S. patent application Ser. No. 09/803702 describes water- andoil-repellent urethane oligomers containing at least one pendantC₄F₉-repeatable unit and at least one C₄F₉— terminal group. PublishedWorld Patent Application WO 01/30873 describes fluorochemicalsulfonamide polymeric surfactants having at least one pendant groupcontaining a C₄F₉— or C₃F₇— moiety.

[0010] The acrylate monomer CF₃CF₂CF₂OCF(CF₃)CH(CF(CF₃)₂)(OC(O)CH═CH₂)is known. Also known is the acrylate monomer CF₂CF₂CF₃CH(CF₃)C(O)CH═CH₂and its polymers and copolymers. The diacrylate monomerCH₂═CHC(O)OCH(CF(CF₃)₂)—(CF₂)₈—CH(CF(CF₃) ₂)(OC(O)CH═CH₂) and itspreparation are disclosed in Published World Application WO 00/50517, aswell as the conversion of the diacrylate monomer to a polymer by UVcuring with a photoinitiator.

SUMMARY OF THE INVENTION

[0011] In one aspect, this invention relates to compounds comprising atleast one acrylate monomer, said monomer comprising at least one pendantgroup of the structure —O—CH(R_(f))(R_(f)′), wherein R_(f) is a straightchain or branched perfluoroalkyl group with five or less carbon atoms,and R_(f)′ is a branched perfluoroalkyl group with three to five carbonatoms.

[0012] In another aspect, this invention relates to a method of treatinga substrate to render it oil-and/or water-repellent comprising treatingthe substrate with a composition comprising a compound that comprises atleast one acrylate monomer, said monomer comprising at least one pendantgroup of the structure —O—CH(R_(f))(R_(f)′), wherein R_(f) is a straightchain or branched perfluoroalkyl group with five or less carbon atoms,and R_(f)′ is a branched perfluoroalkyl group with three to five carbonatoms.

[0013] In still another aspect, this invention relates to a method ofreducing the surface tension of a liquid comprising adding to the liquida compound comprising at least one acrylate monomer, said monomercomprising at least one pendant group of the structure—O—CH(R_(f))(R_(f)′), wherein R_(f) is a straight chain or branchedperfluoroalkyl group with five or less carbon atoms, and R_(f)′ is abranched perfluoroalkyl group with three to five carbon atoms.

[0014] In yet another aspect, this invention relates to an articlecomprising a substrate treated with a composition comprising a compoundcomprising at least one acrylate monomer, said monomer comprising atleast one pendant group of the structure —O—CH(R_(f))(R_(f)′), whereinR_(f) is a straight chain or branched perfluoroalkyl group with five orless carbon atoms, and R_(f)′ is a branched perfluoroalkyl group withthree to five carbon atoms.

[0015] In addition to exhibiting surface energies comparable to knownfluorochemical compounds containing pendant straight-chainperfluorooctyl (C₈F₁₇—) or perfluorobutyl (C₄F₉—) groups, the compoundsof this invention containing pendant —O—CH(R_(f))(R_(f)′) groups offertwo additional advantages. First, the compounds of this inventiongenerally resist hydrolysis under application conditions, possibly dueto steric effects caused by the branched fluoroalkyl chain (e.g., incontrast to polymers made by polymerizing R_(f)CH₂OC(O)CH═CH₂, whereR_(f) is a straight chain or branched perfluoroalkyl group). Second, theexpected ultimate degradation products of compounds of this inventionwill generally have minimal adverse environmental effects because thesedegradation products have a low molecular weight. Oxidation and/orhydrolysis of the compounds will release the fluorinated alcohol orketone. These ketones have at least 5 carbon atoms and have recentlybeen shown to exhibit low toxicity, in contrast to lower carbonatom-containing perfluoroketones such as CF₃C(O)CF₃, which can be verytoxic. Furthermore, some perfluorinated ketones of the formulaR_(f)C(O)R_(f)′ and their corresponding alcohols are known to be cleavedby strong bases to form R_(f)COOH plus R_(f)′H, suggesting that theirenvironmental lifetimes will be short compared with linear R_(f)protective groups. This ketone degradation is especially facile whenR_(f)′ is (CF₃)₂CF—.

[0016] Also, due perhaps to the lack of crystallinity of the amorphousbranched perfluoroalkyl groups and absence of a clearly defined melttransition temperature, the compounds of this invention do not requirecuring at elevated temperatures in order to develop their repellentproperties and thus can be cured at ambient conditions. In contrast,known polymers containing the core crystalline pendant straight-chainperfluoroalkyl groups (e.g., C₈F₁₇— or C₄F₉—) require heat treatment toorient the perfluoroalkyl groups properly in order to fully developtheir repellent properties.

DETAILED DESCRIPTION OF THE INVENTION

[0017] This invention relates to novel amorphous, degradablefluorochemical compounds comprising at least one acrylate monomercomprising polymerizable or a polymer chain of units of the monomer,said compound having at least one pendant group of the structure—O—CH(R_(f))(R_(f)′), wherein R_(f) is a straight chain or branchedperfluoroalkyl group with five or less carbon atoms, and R_(f)′ is abranched perfluoroalkyl group with three to five carbon atoms.

[0018] The compounds of this invention which are also referred to hereinas monomers, oligomers, or polymers of this invention, andfluorochemical acrylate monomers, oligomers, or polymers of theinvention can generally be depicted as shown in Formula I:

[0019] wherein

represents a bond in a polymerizable or a polymer chain;

[0020] R_(f) is a straight chain or branched perfluoroalkyl group withfive or less carbon atoms;

[0021] R_(f)′ is a branched perfluoroalkyl group with three to fivecarbon atoms;

[0022] R is hydrogen, methyl, fluoro or chloro; and

[0023] x is at least 1.

[0024] Preferred monomer compounds are depicted in Formula II:

CH₂═C(R)—C(O)—O—CH(R_(f))(R_(f)′) (II)

[0025] wherein

[0026] R is hydrogen, methyl, fluoro or chloro; and

[0027] R_(f) is a straight chain or branched perfluoroalkyl group withfive or less carbon atoms; and

[0028] R_(f)′ is a branched perfluoroalkyl group with three to fivecarbon atoms.

[0029] Fluorochemical acrylate polymers of this invention contain withinthe polymer backbone (co)polymerized units having the formula depictedin Formula III:

[0030] wherein

[0031] R is hydrogen, methyl, fluoro or chloro; and

[0032] R_(f) is a straight chain or branched perfluoroalkyl group withfive or less carbon atoms;

[0033] R_(f)′ is a branched perfluoroalkyl group with three to fivecarbon atoms; and

[0034] x is at least 2.

[0035] For Formula III, when x has a value from 2 to 10, thefluorochemical acrylate polymer can be considered an oligomer (i.e., avery low molecular weight polymer). Such oligomers are useful assurfactants for coating compositions containing high surface energyorganic materials.

[0036] For Formula III, when x has a value of greater than 10 and up toabout 50, the fluorochemical acrylate polymer is useful as a repellenttreatment for fibrous or hard surface substrates and is useful as anoptical fiber coating.

[0037] For both the acrylate monomers and polymers of this invention,R_(f) is preferably CF₃—, CF₃CF₂—, CF₃CF₂CF₂—, (CF₃)₂CF— or (CF₃)₂CFCF₂— and R_(f)′ is either —CF(CF₃)₂ or —CF₂CF(CF₃)₂. More preferably,R_(f) is CF₃CF₂— or CF₃CF₂CF₂— and R_(f)′ is —CF(CF₃)₂.

[0038] Examples of useful —O—CH(R_(f))(R_(f)′) groups include but arenot limited to —O—CH(CF₃)(CF(CF₃) ₂), —O—(CF(CF₃)₂),—O—CH(CF₂CF₃)(CF(₃)₂), —O—CH(CF(CF₃)₂)₂ and —O—CH(CF₂CF(CF₃)₂)₂.

[0039] The novel fluorochemical acrylate monomers of this invention canbe prepared for example by reacting an alcohol of the formulaHO—CH(R_(f))(R_(f)′) with an acryloyl compound of the formulaCH₂═C(R)—C(O)—X in the presence of a tertiary amine acid scavenger,wherein R_(f), R_(f)′ and R are as defined for Formula II and X is agood leaving group, such as a halogen atom (e.g., Cl or F) or a hydroxylgroup. The alcohol can be prepared for example by reduction with sodiumborohydride of the corresponding perfluoroketone of the formulaR_(f)—C(O)—R_(f)′; see Fokin, A. V., et al.; Bull. Acad. Sci. USSR; EN;27; 8; 1692-1695 (1978); and Saloutina, L. V. et al; J. Org. Chem. USSR;EN; 18; 685-689 (1982).

[0040] The novel fluorochemical acrylate polymers of this invention canbe made for example by homopolymerizing or copolymerizing the monomer ofFormula II, employing free-radical polymerization techniques well knownto one skilled in the art. Useful free-radical initiators include butare not limited to: a persulfate; an azo compound such asazoisobutyronitrile or azo-2-cyanovaleric acid; a hydroperoxide such ascumene, t-butyl, or t-amyl hydroperoxide; a dialkyl peroxide such asdi-t-butyl and dicumyl peroxide; a peroxyester such as t-butylperbenzoate or di-t-butylperoxy phthalate; a diacylperoxide such asbenzoyl peroxide; lauroyl peroxide; and the like. The initiating radicalformed by the initiator can be incorporated into the fluorochemicalacrylate polymer to varying degrees depending on the type and amount ofinitiator used. A suitable amount of initiator depends on the particularinitiator and other reactants being used. About 0.1 percent to about 5percent by weight of an initiator can be used, based on the total weightof the monomers in the reaction, depending upon the desired molecularweight of the fluorochemical acrylate polymer to be made.

[0041] To further control the molecular weight of the polymer, a mono-,di-, or polythiol chain transfer agent can be employed, such as forexample ethanethiol, propanethiol, butanethiol, hexanethiol,n-octylthiol, t-dodecylthiol, 2-mercaptoethyl ether,2-mercaptoimidazole, 2-mercaptoethylsulfide, 2-mercaptoimidazole,8-mercaptomenthone, 2,5-dimercapto-1,3,4-thiadiazole,3,4-toluenedithiol, o-, m-, and p-thiocresol, ethylcyclohexanedithiol,p-menthane-2,9-dithiol, 1,2-ethanedithiol, 3-mercapto-1,2-propanediol,2-mercaptopyrimidine, and the like. The chain transfer agent isgenerally used in an amount of about 0.025 to about 0.2 equivalents, perequivalent of combined olefinic monomers. When oligomers are desired(i.e., where x in formula I is from 2 to 10) higher levels of chaintransfer agent can be employed. The repellent fluorochemical acrylatepolymers of this invention are amorphous materials typically havingglass transition temperatures ranging from about 0° C. to about 60° C.

[0042] In order to achieve the maximum repellent and refractive indexproperties, it is preferred that the fluorochemical acrylate polymer isa homopolymer of the fluorochemical acrylate monomer of this inventionor alternatively is a copolymer of a fluorochemical acrylate monomer ofthe invention and another fluorine-containing acrylate monomer outsidethis invention such as for example CH₂═CHC(O)OCH(CF₃)₂, orCH₂═CHC(O)OCH₂CF₃. However, small amounts (i.e., up to about 25% byweight) of a fluorine-free comonomer, preferably a comonomer that isnon-gaseous under ambient conditions, can be (co)polymerized withoutsignificantly degrading the polymer repellency properties. Forsurfactant applications, higher amounts of fluorine-free comonomer(i.e., up to about 80% by weight) can be (co)polymerized. Usefulfluorine-free comonomers include alkyl acrylate esters, vinyl acetate,vinylidene chloride, styrene, alkyl vinyl ethers, alkyl methacrylateesters, acrylic acid, methacrylic acid, acrylamide, methacrylamide,acrylonitrile, methacrylonitrile, and N-vinylpyrrolidone. Alkyl acrylateesters are preferred fluorine-free comonomers and includestraight-chain, cyclic, and branched-chain isomers of alkyl esterscontaining C₁-C₅₀ alkyl groups. Useful specific examples of alkylacrylate esters include methyl acrylate, ethyl acrylate, n-propylacrylate, 2-butyl acrylate, iso-amyl acrylate, n-hexyl acrylate, heptylacrylate, n-octyl acrylate, iso-octyl acrylate, 2-ethylhexyl acrylate,nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate,tridecyl acrylate, and tetradecyl acrylate.

[0043] Preferably, the free-radical polymerization is carried out insolvent at any suitable concentration, e.g., from about 5 percent toabout 90 percent by weight based on the total weight of the reactionmixture. Examples of suitable solvents include aliphatic and alicyclichydrocarbons (e.g., hexane, heptane, cyclohexane), aromatic solvents(e.g., benzene, toluene, xylene), ethers (e.g., diethylether, glyme,diglyme, diisopropyl ether), esters (e.g., ethyl acetate, butylacetate), alcohols (e.g., ethanol, isopropyl alcohol), ketones (e.g.,acetone, methyl ethyl ketone, methyl isobutyl ketone), sulfoxides (e.g.,dimethyl sulfoxide), amides (e.g., N,N-dimethylformamide,N,N-dimethylacetamide), halogenated solvents (e.g., methylchloroform,FREON™113, trichloroethylene, α,α,α-trifluorotoluene, fluorinated etherssuch as C₄F₉OCH₃, hydrofluorocarbons such as CF₃CFHCFHCF₂CF₃, and thelike), and mixtures thereof Preferably, the solvent is a lowwater-solubility solvent such as an ester (e.g., ethyl acetate or butylacetate), a ketone (e.g., methyl ethyl ketone or methyl isobutylketone), or an ether (e.g., diisopropyl ketone).

[0044] The polymerization to form the desired polymer can be carried outat any temperature suitable for conducting an organic free-radicalreaction. Particular temperature and solvents for use can be easilyselected by those skilled in the art based on considerations such as thesolubility of reagents, the temperature required for the use of aparticular initiator, and the like. While it is not practical toenumerate a particular temperature suitable for all initiators and allsolvents, generally suitable polymerization temperatures are betweenabout 30° C. and about 200° C.

[0045] For oil- and/or water-repellent applications, compounds of theinvention can be most conveniently used as an aqueous composition, inparticular an aqueous dispersion in water. If the compound is first madeby solution polymerization in a solvent, the polymer or oligomer cansubsequently be dispersed in water by vigorously mixing the solutionpolymer or oligomer with water containing cationic, anionic, amphotericand/or nonionic surfactants and, if appropriate, other auxiliaries andsolvents, employing ultrasonic treatment or treatment in a high pressurehomogenizer to provide the energy to form a stable dispersion. Asolvent-free dispersion of the compound can then be obtained bysubsequent removal via distillation of the polymerization solvent.Generally, the aqueous dispersion as a concentrate contains 5 to 50% byweight of polymer or oligomer, 0.5 to 15% by weight of one or moredispersing and/or emulsifying agents, and 0 to 30% by weight of asolvent or solvent mixture, the remainder being water. Alternatively,the aqueous fluorochemical acrylate polymer or oligomer dispersion maybe produced by emulsion polymerization of the fluorochemical acrylatemonomer in water in the presence of a cationic, anionic, amphotericand/or nonionic surfactant, using a water-soluble free-radical initiatorsuch as ammonium persulfate to initiate the polymerization.

[0046] Aqueous solutions or dispersions of the fluorochemical acrylatepolymers may be topically applied onto any substrate, including fibroussubstrates and hard surface substrates to render that substrateresistant to soiling and repellent to water- and oil-based stains. Anytopical method of application that produces a uniform thin coating ofthe polymer on the substrate surface may be employed, such as immersion,flooding, spraying, padding or painting. Once applied from solution ordispersion, the polymer treatment may be dried onto the substrate eitherunder ambient conditions or at elevated temperatures to produce along-lasting altered surface that does not change the appearance of thesubstrate. In the case of porous substrates, the penetration of thepolymer treatment into the porous substrate surface generally preventssignificant adsorption of staining fluids into the substrate (i.e., thefluids will not soak in), even after extensive outdoor exposure, sincethe coating below the surface is not degraded.

[0047] Useful fibrous substrates, which may be protected when topicallytreated with polymers of this invention, include natural textiles andfabrics such as cotton or wool and synthetic fabrics or textiles such aspolyester or nylon, as well as paper and leather(e.g., textiles,carpets, leather, nonwovens, paper). Topical treatment application tofibrous substrates can be accomplished via immersion, spray, foam, kissroll and metering. For example, the substrate can be immersed in adispersion or solution of the fluorochemical acrylate polymer andagitated until it is saturated. The saturated fibrous substrate can thenbe run through a padder/roller to remove excess dispersion, dried in anoven at a relatively low temperature (e.g., at 70° C.) for a timesufficient to remove the dispersion medium (e.g. solvents such as thoseused in the polymerization reaction), and cured at a temperature and fora time sufficient to provide a cured treated substrate. This curingprocess can be carried out at temperatures between ambient temperatureand about 150° C. depending on the particular composition used. Ingeneral, a temperature of about 40 to 150° C. for a period of about 10minutes is suitable. The cured treated fibrous substrate can be cooledto room temperature and used as desired, e.g., incorporated or fashionedinto apparel or upholstery.

[0048] Hard surface substrates which may be protected when topicallytreated with the fluorochemical acrylate polymers of this inventioninclude porous hard surfaces such as masonry (i.e., human-made hardporous materials such as concrete, brick, tile, grout) and stone (i.e.,naturally occurring porous materials), substrates used extensively inthe construction of buildings, roads, parking ramps, driveways, garageflooring, fireplaces, fireplace hearths, and counter tops. When leftunprotected, masonry and stone surfaces quickly discolor from exposureto water- and oil-based stains and gradually deteriorate from spallingand efflorescence induced by water penetration and weather exposure.Protection against discoloration from common water- and oil-basedhousehold liquids such as motor oil, brake-oil, transmission fluid,cooking oil, coffee, and wine is highly desirable due to the high costand labor of replacing such materials. For these massive and immobilesubstrates, application of treating liquids is most conveniently done bybrush, roller or spray and cure must be accomplished at ambienttemperature.

[0049] The fluorochemical acrylate polymers of this invention may alsobe used as low refractive index coatings, particularly for coatingoptical fibers. Typically, optical fibers comprise a light carryingcore, for example an inorganic glass such as fused silica or a polymersuch as polymethyl methacrylate, and a cladding material having a lowerrefractive index than the core. By having a lower refractive index, thecladding material serves to confine the light energy within the core andthereby allows propagation of light by a phenomenon generally known as“total internal reflection.” Fiber-guided modulated light beams areuseful in many applications, for example, telecommunications, computerlink-ups, and automotive controls. Advantageously, fiber optic linkageshave a greater information carrying capacity as compared to metal wirescarrying electrical signals. Furthermore, fiber optics are less likelyto suffer from external interference, such as electromagnetic radiation.

[0050] The fluorochemical acrylate polymers of this invention can alsobe employed to apply a coating to an electrical device. Such coatingapplications include anti-stiction coatings for computer hard drives,barrier coatings to protect sensitive substrates such as circuit boards,and antimigration coatings to prevent the migration of lubricants.Copolymers of the fluorochemical acrylate monomer with for example asmall amount of (meth)acrylic acid (i.e., less than 10% by weight,preferably less than 5% by weight) can improve the adhesion of thefluorochemical acrylate polymer to polar substrates such as the metalcircuits etched on circuit boards or the metallic surfaces of computerhard drives or optical pellicle frames.

[0051] The amount of the fluorochemical compound applied to a substratein accordance with this invention is chosen so that desirably highsurface modification (e.g., water and/or oil repellency, refractiveindex reduction) is imparted to the substrate surface, said amountusually being such that 0.01% to 5% by weight, preferably 0.05 to 2% byweight, of fluorine is present on the treated substrate. The amount,which is sufficient to impart desired repellency or refractive indexreduction, can be determined empirically and can be increased asnecessary or desired.

[0052] The fluorochemical acrylate polymers of this invention are alsouseful as surfactants for lowering the surface tension of liquids andthus can be employed to improve the wetting properties of coatingcompositions containing high surface energy organic materials. Such“difficult-to-wet-with” materials include thermoset resins (e.g., highsolids formulations containing epoxy resins, acrylic resins, aminoplastsand/or polyols) and thermoplastic resins (e.g., plasticized polyvinylchloride dispersions). Particularly useful as surfactants are copolymersof the fluorochemical acrylate monomers of this invention withpolyoxyalkylene acrylate esters, such as the acrylate esters ofPLURONIC™ propylene oxide/ethylene oxide copolymers (copolymersavailable from BASF Corp., Mount Olive, N.J.) or the acrylate esters ofCARBOWAX™ polyethylene glycols (glycols available from Union CarbideCorp., South Charleston, W. Va.). An effective use level for thesurfactants is at least 0.1%, preferably at least 0.2%, and morepreferably at least 0.5% by weight of the high surface energy organicmaterial.

EXAMPLES

[0053] Objects and advantages of this invention are further illustratedby the following examples, but the particular materials and amountsthereof recited in these examples, as well as other conditions anddetails, should not be construed to unduly limit this invention. Unlessotherwise specified, all percentages and proportions are by weight.

Test Methods

[0054] The test methods used to evaluate the performance described inthe later-described Examples and Comparative Examples are describedbelow.

[0055] Glass Transition Temperature (Tg)—For each glass transitiontemperature determination, the sample used consisted of polymer solidsobtained by removing the solvent from the polymer solution by drying thesolution in a forced air oven at 100° C. for at least 30 minutes. Theglass transition temperature (Tg) of each sample was determined byDifferential Scanning Calorimetry using a Perkin-Elmer 7-Series ThermalAnalysis System (Perkin-Elmer Corp., Norwalk, Conn.) with a generaltemperature range of −50 to 200° C. Tg values were determined accordingto ASTM protocol E1356-91 except a 20° C./minute ramp was used. If atransition could not be found in the general range, the temperaturerange was expanded as needed. Measurements were made after two heat andcool cycles. The Tg was recorded as a midpoint determination of thepoint at which the derivative of the interpolated slope of thetransition equaled zero.

[0056] Advancing and Receding Contact Angle Test—The Advancing andReceding Contact Angle Test provides a quick and precise prediction ofthe surface properties of a coating material. Advancing and Recedingcontact angle values measured with water and n-hexadecane using thistest have correlated well with fluid repellency values measured onfabrics and carpets.

[0057] To run this test, a solution, emulsion, or suspension (typicallyat about 3% solids) is applied to a polymer film (nylon or polyester) bydip-coating. The polymer film is prepared as follows. Polymer film iscut into 85 mm×13 mm rectangular strips. Each strip is cleaned bydipping into methyl alcohol, wiping with a KIMWIPE™ wiper (commerciallyavailable from Kimberly-Clark Corp., Neenah, Wis.), taking care not totouch the strip's surface, and allowing the strip to dry for 15 minutes.Then, using a small binder clip to hold one end of the strip, the stripis immersed in the treating solution, and the strip is withdrawn slowlyand smoothly from the solution. The coated film strip is tilted to allowany solution run-off to accumulate at the corner of the strip, and aKIMWIPE™ wiper is touched to the corner to pull away the solutionbuildup. The coated film strip is allowed to air dry in a protectedlocation for a minimum of 30 minutes and then cured for 10 minutes at121° C. unless otherwise indicated.

[0058] After the treatment is dry and cured, the advancing and recedingcontact angles are measured using a CAHN Dynamic Contact Angle Analyzer,Model DCA 322 (a Wilhelmy balance apparatus equipped with a computer forcontrol and data processing, commercially available from ATI, Madison,Wis.). The CAHN Dynamic Contact Angle Analyzer is calibrated using a 500mg weight. An alligator clip is fastened to a piece of coated film stripabout 30 mm long, and the clip and film piece are hung from the stirrupof the balance. A 30 mL glass beaker containing approximately 25 mL ofwater or n-hexadecane is placed under the balance stirrup, and thebeaker is positioned so that the coated film strip is centered over thebeaker and its contents but not touching the walls of the beaker. Usingthe lever on the left side of the apparatus, the platform supporting thebeaker is carefully raised until the surface of water or n-hexadecane is2-3 mm from the lower edge of the film strip. The door to the apparatusis closed, the “Configure” option is chosen from the “Initialize” menuof the computer, the “Automatic” option is chosen from the “Experiment”menu, and the computer program then calculates the time for a scan. Theapparatus then raises and lowers the liquid so that the scan is taken(the advancing angle is measured as the liquid moves up and over thesurface, while the receding angle is determined as the liquid moves downand away from the surface of the plastic film). The “Least Squares”option is then selected from the “Analysis” menu, and the averagereceding contact angle is calculated from the scan of the film sample.Three separate films are prepared for each material to be tested aspreviously described. The 95% confidence interval for the average of the3 scans is typically about 1.2°. This procedure is repeated for waterand n-hexadecane.

[0059] Surface Tension Measurement—All surface tension measurements forthe polymeric surfactants were made using a Krüss K-12 Tensiometerintegrated with an automatic dosimat and a computer equipped with a K121software package (available from Krüss U.S.A, Charlotte, N.C.). Theprogram was run using a Wilhelmy platinum plate (PL 12) and glass samplevessel (GL7).

Preparation of Compounds

[0060] Polymer 1.

[0061] Preparation of CH₂═CHC(O)—O—CH(CF₃)(CF(CF₃)₂) Homopolymer

[0062] Perfluoro(methyl isopropyl ketone) (64 g, 0.24 mol, can beprepared as described in Example 5 of World Published Application WO01/05468) was reduced to the corresponding alcohol with NaBH₄ (10.9 g,0.29 mol, available from Sigma-Aldrich Chemical Co., Milwaukee, Wis.) in235 mL anhydrous diglyme (anhydrous diethylene glycol dimethyl ether,available from Sigma-Aldrich Chemical Co.) at approximately 0° C. Thereaction mixture was quenched with cold 10% aqueous HCI (200 miL). Thelower phase was isolated, washed twice with 200 mL aliquots of saturatedNaCl solution at 0° C., dried over anhydrous MgSO₄ and filtered to givea filtrate (80.7 g). The solvent was distilled from the filtrate toproduce 56.7 g of1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-2-butanol with a yield of88% (b.p.=100-140° C.). Analysis by proton and fluorine NMR showed thefollowing peaks: −72.5(3F), −75.5(3F), −74.3(3F), −182.7(1F), 4.6 (1H),3.8 (1H).

[0063] 25.7 g (0.096 mol) of the1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-2-butanol was dissolved indiglyme (50 ml) and the resulting solution was cooled to 5° C. under anitrogen blanket. Acryloyl chloride (9.5 g, 0.105 mol, available fromSigma-Aldrich Chemical Company) was added to this solution by syringewhile stirring. To this solution was added diisopropylethyl amine (13.6g, 0.105 mol, available from Sigma-Aldrich Chemical Co.) dropwise over aperiod of 35 minutes. After 2 hours, the reaction mixture was filteredto remove the solid by-products and the filtrate was diluted withmethylene chloride (40 mL). The filtrate was then washed three timeswith 75 ML aliquots of saturated NaCl solution, dried over anhydrousMgSO₄, filtered, and the solvent removed by rotary evaporation to leavea residue of 22 g of crude acrylate ester. The acrylate ester waspurified via column chromatography using silica gel to produce 16.2 g ofpurified ester. Fluorine NMR analysis showed the following peaks: −74.3(3F), −75.5(3F), −182.7(1F), −72.4(3F). Proton NMR analysis showed thefollowing peaks: 6.15 (1H), and 3 olefinic hydrogens at 6.6, 6.2, and6.1 ppm.

[0064] The purified acrylate ester (5.5 g, 0.017 mol) and VAZO™ 64initiator (28 mg) was then dissolved in 30 g of ethyl acetate in a 4 oz(110 g) polymerization bottle. The solution was purged for 90 secondsusing N₂ at 1 L/min, then polymerization was affected by heating thesolution for 26 hours by rotating the bottle in a heated water bath.After the polymerization, the solvent was removed by rotary evaporation.The resulting yellow oil was twice dissolved in acetone and precipitatedfrom solution with chloroform. The resulting solid was collected byfiltration and dried. The structure of the homopolymer was verified byproton and fluorine NMR. Tg was 53.9° C. with onset at 27.7° C. Thesolid collected by filtration was dissolved at 3% solids in C₄F₉OCH₃(available as HFE-7100 Engineering Fluid from 3M Company, St. Paul,Minn.).

[0065] Polymer 2.

[0066] Preparation of CH₂═CHC(O)—O—CH(CF₂CF₃)(CF(CF₃)₂) Homopolymer

[0067] Perfluoro(ethyl isopropyl ketone) (151 g, can be prepared asdescribed in Example 1 of World Published Application WO 01/05468) wasslowly added to a stirred mixture of 14.0 g NaBH₄ in 150 mL anhydroustetraglyme (available from Sigma-Aldrich Chemical Co., Milwaukee, Wis.),controlling the exotherm with an ice bath. Cautious workup with about100 mL methanol and then about 300 mL 5% aqueous HCl, followed byextraction with C₄F₉OCH₃ and distillation, yielded 129.6 gC₂F₅CH(OH)CF(CF₃)₂ (b.p. 88° C.).

[0068] A solution containing 61.5 g of the resulting alcohol and 14.5 gN,N-diisopropylethyl amine (available from Sigma-Aldrich Chemical Co.)in 150 mL methylene chloride was treated with 9.5 g acryloyl chloride(available from Sigma-Aldrich Chemical Co.). After washing with 5%aqueous sulfuric acid, the reaction product was treated with a smallamount of phenothiazine (available from Sigma-Aldrich Chemical Co.),concentrated, and distilled at 30° C. and approximately 5 torr toprovide a main acrylate ester monomer cut. The recovered monomer had arefractive index of 1.3186 measured at 21.3° C. For comparison, therefractive index of C₇F₁₅CH₂OC(O)CH═CH₂, a monomer interpolymerized inlow refractive index polymer used for coating glass optical fibers, hada slightly higher measured refractive index of 1.3289. (Low refractiveindexes are preferred.)

[0069] 10.0 g of the resulting acrylate ester monomer was mixed with 30g ethyl acetate (EtOAc) in a 4 oz (110 g) bottle and was polymerizedusing 100 mg VAZO™ 64 initiator (2,2′-azobisisobutyronitrile, availablefrom E. I. duPont de Nemours & Co., Wilmington, Del.). The resultingsolution was purged for 35 seconds using N₂ at 1 L/min, then heated for22 hours by rotating the bottle in a heated water bath set at 60° C. Thepolymer that precipitated during the reaction (3.2 g, Tg=33° C.) wasseparated and dissolved at 3% solids in C₄F₉OCH₃.

[0070] Polymer 3.

[0071] Preparation of CH₂═CHC(O)—O—CH(C₃F₇)(CF(CF₃)₂) Homopolymer

[0072] C₃F₇CH(OH)CF(CF₃)₂ (where C₃F₇ represents an approximately 45/55blend of n-C₃F₇ and i-C₃F₇) was prepared by reduction of thecorresponding ketone, C₃F₇C(O)CF(CF₃)₂ (can be prepared as described inExample 3 of World Published Application WO 01/05468), using theborohydride reduction procedure described in the preparation of Polymer2. The resulting alcohol was converted to the corresponding acrylateester monomer by esterification with acryloyl chloride, also describedin the preparation of Polymer 2 (b.p. 38-60° C. at 15 torr).

[0073] A homopolymer acrylate was then prepared by homopolymerizing 10.0g acrylate ester monomer in 30 g EtOAc using 76 mg VAZO™ 64 initiator.The resulting precipitated homopolymer had a Tg of 11° C. Thehomopolymer was dissolved at 3% solids in C₄F₉OCH₃.

[0074] Polymer 4.

[0075] Preparation of CH₂═CHC(O)—O—CH(CF(CF₃)₂)₂ Homopolymer

[0076] Perfluoro(diisopropyl ketone)(96.5 g, 0.26 mol, can be preparedas described in Example 5 of World Published Application WO 01/05468)was reduced to the corresponding alcohol, [(CF₃)₂CF]₂CHOH, by reactingthe ketone with NaBH₄ (11 g, 0.29 mol) in 250 mL of anhydrous diglyme(anhydrous diethylene glycol dimethyl ether, available fromSigma-Aldrich Chemical Co.) at approximately 0° C. The reaction mixturewas quenched with cold 10% aqueous HCl (250 mL). The mixture was washedwith 250 mL of 10% aqueous HCI and 250 mL of saturated NaCl solution (atapproximately 0° C.), dried over anhydrous MgSO₄, and filtered. Thefiltrate was distilled to produce 81.6 g of1,1,1,2,4,5,5,5-octafluoro-2,4-bis-trifluoromethyl-pentan-3-ol(b.p.=112-114° C.). Analysis by proton and fluorine NMR (neatfluid+CFCl₃ & TMS) showed the following peaks: −71.0 (6F), −76.7(6F),−182.4(2F), 5.3 (1H, quartet), 6.5 (1H, doublet).

[0077] The alcohol was esterified to the corresponding acrylate monomerby reaction with acryloyl chloride in the presence of triethylamine(boiling range =42-44° C. at 14 torr). The fluorochemical acrylatehomopolymer was then prepared by polymerizing 5.0 g fluorochemicalacrylate monomer using 0.05 g VAZO™ 64 initiator in 50 mL ethyl acetate.The homopolymer was precipitated from the ethyl acetate solution,filtered, washed with fresh ethyl acetate, and dried. The dried polymerwas dissolved at 3% solids in C₄F₉OCH₃.

[0078] Polymer 5.

[0079] Preparation of CH₂═CHC(O)—O—CH(CF₂CF(CF₃)₂)₂ Homopolymer

[0080] Direct fluorination of 624.2 g (3.35 mol) 2,6-dimethyl-4-heptylacetate (made by reacting 2,6-dimethyl-4-heptanol (available fromSigma-Aldrich Chemical Co.) and acetyl chloride, b.p.=40-46° C. at 1torr) in perfluoro-N-methylmorpholine solvent was conducted in a tubularreactor at 35° C., as described in U.S. Pat. No. 5,578,278. The solventwas removed by distillation to leave 1583.5 g of opaque tan liquid,shown by gas-liquid chromatography (glc) to contain primarily two maincomponents, 31% perfluoro-2,6-dimethyl-4-heptanone and 53%4H-perfluoro-(2,6-dimethyl-4-heptyl)trifluoroacetate). The tan liquidwas filtered and distilled to yield a series of fractions boiling from110° C./745 torr to 90° C./40 torr, with the ketone predominant in theinitial fractions. The initial fractions were recombined to form amixture containing approximately 419 g (0.88 mol) ketone and 764 g (1.35mol) trifluoroacetate, for an overall yield of 67% of crude product.4H-perfluoro-2,6-dimethyl-4-heptanol was prepared from thisketone-containing mixture and mixtures prepared in a similar fashion byusing several methods. The first method employed treatment of 1305 g ofcrude ketone product with 200 mL 14% BF₃ in methanol (available fromSigma-Aldrich Chemical Co.) at ice temperature, quenching the product inwater, and distilling the product to give 664 g of alcohol(b.p.=140-170° C.). Alternatively, a mixture containing 530 g of adistillate containing 32% ketone-64% 4H ester and 300 g 25% aqueous NaOHwas vigorously stirred at 70° C. for 18 hours, acidified with 25%aqueous sulfuric acid and distilled to give 233 g of alcohol(b.p.=140-150° C.). In a preferred alternative, 246 g of a distillatecontaining 58% ketone-30% 4H ester was reduced with 13.8 g NaBH₄ to give208 g of alcohol (b.p.=138-146° C.). This alcohol proved unreactive totrifluoroacetic anhydride, which is indicative of extreme sterichindrance about the hydroxyl group.

[0081] A mixture consisting of 501.2 g distilled alcohol, 96.4 gacryloyl chloride, 150 mL CFC-113, and 150 mL methylene chloride wascooled using ice and treated dropwise with 107 g triethylamine(available from Sigma-Aldrich Chemical Co.). The reaction mixture wasworked up as described in Polymer 2 to provide 426 g acrylate estermonomer (b.p.=55-60° C. at 1.2 torr). A mixture of 10 g acrylate estermonomer, 25 g EtOAc, and 75 mg VAZO™ 64 initiator was heated for 24hours using a steam bath at 60-70° C. to give an insoluble polymer thatdried to a brittle white solid (Tg=36° C.; TGA (air): 10% loss at 300°C., 50% loss at 350° C.). The dried polymer was dissolved at 3% solidsin C₄F₉OCH₃.

[0082] Polymer 6.

[0083] Preparation of CH₂=CHC(O)OCH(CF₃)₂ Homopolymer

[0084] To a 4 oz (110 g) narrow mouth amber bottle were added 10 g of1,1,1,3,3,3-hexafluoroisopropyl acrylate (CH₂═CHC(O)OCH(CF₃)₂, 99% pure,refractive index of 1.3190 at 20° C., available from Fluorochem USA,West Columbia, S.C.), 0.05 g of VAZO™ 64 initiator and 40 g of C₄F₉OCH₃.The bottle and contents were purged with nitrogen gas for approximatelyone minute, then the bottle was capped securely. The bottle and contentswere then tumbled in a constant temperature water bath at 65° C. for 18hours. After the polymerization, the reaction mixture was diluted to 3%concentration with C₄F₉OCH₃.

[0085] Polymer 7.

[0086] Preparation of CH₂═CHC(O)OC₂H₄O(CF₃)═C(CF(CF₃)₂)₂ Homopolymer

[0087] Into a flask equipped with stirrer and heater was placed 18.0 ghexafluoropropylene trimer (available from Lancaster Synthesis, Inc.,Windham, N.H.), 4.05 g triethylamine and 30 mL tetrahydrofuran. To thismixture was slowly added 4.8 g 2-hydroxyethyl acrylate (available fromSigma-Aldrich Chemical Co.). The resulting two phase system was heatedto about 45° C. and became a single phase after 20 minutes, indicatingthe end of the reaction. The reaction product was dissolved in1,1,2-trifluoro-1,2,2-trichloroethane, washed with water, and distilledfrom phenothiazine to yield the monomerCH₂═CHC(O)OC₂H₄O(CF₃)═C(CF(CF₃)₂)₂, a yellow liquid boiling at 84-85°C./0.6

[0088] Following the general procedure described for the preparation ofPolymer 5, a polymer was made by homopolymerizing 5 g ofCH₂═CHC(O)OC₂H₄O(CF₃)═C(CF(CF₃)₂)₂ monomer in 26.4 g EtOAc for 24 hoursat 60° C. using 37 mg of VAZO™ 64 initiator, resulting in a clearsolution. The polymer was precipitated from solution using methylalcohol, a sample was dried, and the measured Tg was 45° C. Theremaining polymer was then dissolved in1,1,2-trifluoro-1,2,2-trichloroethane to form a clear solution.

[0089] Polymer 8.

[0090] Preparation of CH₂═CHC(O)—O—CH(CF₃)(C₆F₁₃) Homopolymer

[0091] 100 g perfluoro(2-octanone) (can be prepared as described inExample 4 of World Published Application WO 01/05468) in 100 gperfluorohexane (available as FLUORINERT™ FC-72 from 3M Co.) was reducedover 0.82 g of 10% Pd/C catalyst (available from Sigma-Aldrich ChemicalCo.) in a low-pressure Parr hydrogenator, as measured by rapid uptake ofH₂. Distillation provided 78.9 g of the alcohol (b.p. 128-130 ° C.).20.9 g of this alcohol was converted to 19.5 g acrylate ester monomer asdescribed for Polymer 1 (b.p.=93° C. at 63 torr, refractive index=1.3172at 23° C.). A mixture of 10.0 g acrylate ester monomer, 30 g EtOAc, and100 mg VAZO™ 64 initiator was heated for 24 hours using a steam bath at60° C. to give 7.2 g of an insoluble polymer that dried to a brittlewhite solid (Tg=11° C.). The dried polymer was dissolved at 3% solids inC₄F₉OCH₃.

[0092] Polymer 9.

[0093] Preparation of C₈F₁₇SO₂N(C₂H₅)C₂H₄OC(O)CH═CH₂ Homopolymer

[0094] To an 8 ounce (220 g) narrow mouth amber bottle were added 20 gof C₈F₁₇SO₂N(C₂H₅)C₂H₄OC(O)CH═CH₂ (“MeFOSEA” monomer, can be preparedusing the general procedure described in U.S. Pat. No. 2,803,615), 0.2 gof VAZO™ 64 initiator and 80 g of C₄F₉OCH₃. The bottle was purged withnitrogen gas for approximately one minute, then capped securely. Thebottle and its contents were then tumbled in a constant temperaturewater bath at 65° C. for 18 hours. The reaction mixture was diluted to3% solids in C₄F₉OCH₃ before testing.

[0095] Polymer 10.

[0096] Preparation of C₈F₁₇CH₂CH₂OC(O)CH═CH₂ Homopolymer

[0097] Essentially the same procedure was followed as described for thesynthesis of Polymer 9, except that 20 g of C₈F₁₇CH₂CH₂OC(O)CH═CH₂(“FOEA” monomer, can be prepared by reacting ZONYL™ BA alcohol(available from E. I. duPont de Nemours & Co., Wilmington, Del.) withacryloyl chloride) was substituted for 20 g of MeFOSEA monomer.

[0098] Polymer 11.

[0099] Preparation of 75/25 C₈F₁₇SO₂N(CH₃)C₂H₄OC(O)CH═CH₂/C₄H₉OC(O)CH═CH₂ copolymer

[0100] Essentially the same procedure was followed as described for thesynthesis of Polymer 9, except that 5 g of n-butyl acrylate (availablefrom Sigma-Aldrich Chemical Co.) was substituted for 5 g (one quarter)of the MeFOSEA monomer.

[0101] Polymer 12.

[0102] Preparation of C₈C₁₇SO₂N(C₄H₉)C₂H₄OC(O)CH═CH₂ Homopolymer

[0103] Essentially the same procedure was followed as described for thesynthesis of Polymer 9, except that 20 g ofC₈F₁₇SO₂N(C₄H₉)C₂H₄OC(O)CH═CH₂ (“BuFOSEA” monomer, available as FLUORAD™FX-189 intermediate from 3M Company) was substituted for 20 g of MeFOSEAmonomer.

[0104] Polymer 13.

[0105] Preparation of 98.8/1.2 CH₂═CH—C(O)—O—CH(C₂F₅)(CF(CF₃)₂)/AACopolymer

[0106] Into a flask equipped with an overhead stirrer, a thermocoupleand an addition funnel was placed 25 g (0.067 mol) of1-pentafluoroethyl-2-(trifluoromethyl)-2,3,3,3-tetrafluoropropylacrylate ester, 0.3 g (0.0042 mol) of acrylic acid (AA, available fromSigma-Aldrich Chemical Co.), 143 g of C₄F₉OC₂H₅ (available as NOVEC™HFE-7200 engineering fluid from 3M Company) and 1.01 g of LUPEROX™26-M50 initiator (50% solution in mineral spirits, available from ElfAtochem North America, Philadelphia, Pa.). The resulting solution wasdegassed several times using a nitrogen stream, and the polymerizationwas carried out at 73° C. for 16 hours. The resulting polymer wascompletely soluble in C₄F₉OC₂H₅ so the reaction solution was poured intomethanol, causing the polymer to precipitate. The precipitate wasseparated, air dried and subsequently redissolved in C₄F₉OCH₃ to give an8.3% solids solution. The solution was further diluted with C₄F₉OCH₃ togive a 3% solids solution. The Tg for this polymer was 16° C.

[0107] The 1 -pentafluoroethyl-2-(trifluoromethyl)-2,3,3,3-tetrafluoropropyl acrylate ester was prepared from the alcohol byreacting the alcohol with acryloyl chloride using a tertiary aminecatalyst, N,N-diisopropylethyl amine, as described for Polymer 1

[0108] The1-pentafluoroethyl-2-(trifluoromethyl)-2,3,3,3-tetrafluoropropyl alcoholwas prepared as follows. Into a flask equipped with an overhead stirrer,a thermocouple and an addition funnel were placed 53.9 g (1.47 mol) ofNaBH₄ and 500 mL of tetraethylene glycol diethyl ether. The resultingmixture was cooled to under 10° C., and 37.5 g (1.19 mol) of1,1,1,2,4,4,5,5,5-nonafluoro-2-trifluoromethyl-pentan-3-one was addedover approximately a four hour period, keeping the reaction mixturetemperature under 17° C. The reaction mixture was then stirred for 1hour, allowing the temperature to warm to 15° C. The reaction mixturewas then cooled back down to 5° C. using an ice bath, and 10% aqueousHCI was added in two 250 mL aliquots, adding the aqueous acid slowlyover a 2 hour time period to minimize foaming. Next, an additional 400mL of 10% aqueous HCI was added to completely dissolve the solids. Themixture was transferred to a 2-L separatory funnel and the clear lowerphase was saved. The upper aqueous phase was then extracted with a 200mL aliquot of perfluorohexane and was combined with the lower phase. Theresidual water was removed by distillation with a Dean Stark trap withreturn. The resulting1-pentafluoroethyl-2-(trifluoromethyl)-2,3,3,3-tetrafluoropropyl alcoholproduct was distilled at 98° C. to obtain 303.5 g of product (80%yield).

[0109] The precursor1,1,1,2,4,4,5,5,5-nonafluoro-2-trifluoromethyl-pentan-3-one,CF₃CF₂C(O)CF(CF₃)₂, was prepared as follows. Into a clean dry 600 mLParr reactor equipped with a stirrer, a heater and a thermocouple wereadded 5.6 g (0.10 mol) of anhydrous potassium fluoride and 250 g ofanhydrous diglyme. The anhydrous potassium fluoride used in thissynthesis was spray dried, stored at 125° C. and ground shortly beforeuse. The contents of the reactor were then stirred while 21.0 g (0.13mol) of C₂F₅COF (approximately 95.0% purity) was added to the sealedreactor. The reactor and its contents were then heated, and once atemperature of 70° C. was reached, a mixture of 147.3 g (0.98 mol) ofCF₂═CFCF₃ (hexafluoropropylene) and 163.3 g (0.98 mol) of C₂F₅COF wasadded over a 3.0 hour time period. During the addition of thehexafluoropropylene and the C₂F₅COF mixture, the pressure was maintainedat less than 95 psig (7500 torr). The pressure at the end of thehexafluoropropylene addition was 30 psig (2300 torr) and did not changeover the 45-minute hold period. The reactor contents were allowed tocool and were one-plate distilled to obtain 307.1 g containing 90.6%1,1,1,2,4,4,5,5,5-nonafluoro-2-trifluoromethyl-pentan-3and 0.37% C₆F₁₂(hexafluoropropylene dimers) as determined by gas chromatography. Thecrude fluorinated ketone was water-washed, distilled, and dried bycontact with silica gel to provide a fractionated fluorinated ketone of99% purity that contained 0.4% hexafluoropropylene dimers.

[0110] Polymer 14.

[0111] Preparation of 98.8/1.2 CH₂═CH—C(O)—O—CH(C₂F₅)(CF(CF₃)₂)/MAACopolymer

[0112] Polymer 14 was prepared using essentially the same procedure asdescribed for the preparation of Polymer 13. In this case, 23.8 g (0.064mol) of 1-pentafluoroethyl-2-(trifluoromethyl)-2,3,3,3-tetrafluoropropylacrylate (monomer prepared as described for Polymer 13) and 0.33 g(0.0038 mol) of methacrylic acid (MAA, available from Sigma-AldrichChemical Co.) were copolymerized in 136 g of C₄F₉OC₂H₅ using LUPEROX™26-M50 initiator (0.96 g of 50% solution in mineral spirits) by heatingat 73° C. for 16 hours. The resulting copolymer was precipitated fromsolution in C₄F₉OC₂H₅ by addition of methanol. The precipitate wasisolated by decantation, air-dried and then dissolved at 11.9% solids inC₄F₉OCH₃. The resulting solution was further diluted to 3% solids withadditional C₄F₉OCH₃ before testing. The resulting copolymer had a Tg of2.3° C.

[0113] Polymer 15.

[0114] Preparation of 25/75 CH₂═CH—C(O)—O—CH(CF₂CF₃(CF(CF₃)₂)/PLURONIC™L-44 Acrylate Copolymer

[0115] Into a 1-L, 3-necked round bottom flask equipped with an overheadstirrer, a water condenser, a thermocouple and a source of dry nitrogenwere added CH₂═CHC(O)—O—CH(CF₂CF₃)(CF(CF₃)₂) (30 g), PLURONIC™ L-44acrylate (140 g, about 63% solids in toluene) (theoreticallyHO(CH₂CH₂O)₁₁[CH(CH₃)CH₂O]₂₁(CH₂CH₂O)₁₁C(O)CH═CH₂), can be prepared asdescribed in Example 1 of U.S. Pat. No. 3,787,351), VAZO™ 64 initiator(3.6 g), 3-mercapto-1,2-propanediol chain transfer agent (7.2 g,available from Sigma-Aldrich Chemical Co.) and toluene (194 g). Theresulting solution was de-gassed several times using dry nitrogen andwas then heated to 79° C. with stirring. After a brief exotherm to 84°C., the temperature was maintained at 79° C. for 6 hours. The toluenewas then removed from the polymer reaction product using rotaryevaporation at 55° C. and water aspirator vacuum to yield 111 g ofpolymeric surfactant product.

[0116] Polymer 16.

[0117] Preparation of 25/75CH₂═CH—C(O)—O—CH(CF₂CF₂CF₃)(CF(CF₃)₂)/PLURONIC™ L-44 Acrylate Copolymer

[0118] Into a 1-L, 3-necked round bottom flask equipped with an overheadstirrer, a water condenser, a thermocouple and a source of dry nitrogenwere added CH₂═CHC(O)—O—CH(CF₂CF₂CF₃)(CF(CF₃)₂) (10 g), PLURONIC™ L-44acrylate (46.7 g, about 63% solids in toluene), VAZO™ 64 initiator (1.2g), 3-mercapto-1,2-propanediol chain transfer agent (2.4 g) and toluene(65 g). The resulting solution was de-gassed several times using drynitrogen and was then heated to 79° C. with stirring for 6 hours. Thetoluene was then removed from the polymer reaction product using rotaryevaporation at 55° C. and water aspirator vacuum to yield 45 g ofpolymeric surfactant product.

[0119] Polymer 17.

[0120] Preparation of 22/78 C₄F₉SO₂N(CH₃)C₂H₄OC(O)CH═CH₂/PLURONIC™ L-44Acrylate Copolymer

[0121] This copolymer can be prepared using the procedure described inExample 4 of World Published Patent Application WO 01/30873.

[0122] Polymer 18.

[0123] Preparation of 99/1 CH₂═CHC(O)—O—CH(CF₂CF(CF₃)₂)₂/AA Copolymer

[0124] Following the general procedure described for the preparation ofPolymer 5, 9.9 g CH₂═CHC(O)—O—CH(CF₂CF(CF₃)₂)₂ was copolymerized with0.1 g acrylic acid in 30 g EtOAc for 22 hours at 60° C. using 75 mgVAZO™ 64 initiator. No performance evaluations were conducted with thiscopolymer.

[0125] Polymers 19-21.

[0126] Preparation of CH₂═CHC(O)—O—CH(CF₂CF(CF₃)₂)₂/VCl₂ Copolymers

[0127] Following the general procedure described for the preparation ofPolymer 5, a series of copolymers, Polymer 19, 20 and 21, were made bycopolymerizing CH₂═CHC(O)—O —CH(CF₂CF(CF₃)₂)₂ (FC monomer) withvinylidene chloride (VCl₂, available from Sigma-Aldrich Chemical Co.) in40 g EtOAc for 22 hours at 60° C. using 150 mg of VAZO™ 64 initiator.

[0128] The following amounts of each monomer were used to make eachcopolymer:

[0129] Polymer 19: 16 g FC monomer, 4 g VCl₂ (80/20 copolymer)

[0130] Polymer 20: 18 g FC monomer, 2 g VCl₂ (90/10 copolymer)

[0131] Polymer 21: 19 g FC monomer, 1 g VCl₂ (95/5 copolymer)

[0132] For Polymer 20, the measured Tg was 37.8° C.

Examples 1-5

[0133] Glass transition temperatures (Tg) and advancing and recedingcontact angles (ACA and RCA) vs. water and n-hexadecane (n-C₁₆H₃₄) weremeasured for Polymers 1-5, several fluorochemical homopolymers of thisinvention containing pendant —O—CH(R_(f))(R_(f)′) groups. Eachhomopolymer was coated onto polyester film from a 3% solids polymersolution in either C₄F₉OCH₃ (available as NOVEC™ HFE-7100 engineeringfluid from 3M Company, St. Paul, Minn.) or α,α,α-trifluorotoluene(available from Sigma-Aldrich Chemical Co., Milwaukee, Wis.). The coatedfilm was then cured for 24 hours at ambient temperature prior to contactangle testing.

[0134] Results are presented in TABLE 1; the R_(f) and R_(f)′ group isindicated for each homopolymer. TABLE 1 n- Tg, Water: Hexadecane: Ex.Polymer R_(f) R′_(f) ° C. ACA RCA ACA RCA 1 1 CF₃— (CF₃)₂CF— 54 118 7368 49 2 2 C₂F₅— (CF₃)₂CF— 33 118 98 69 62 3 3 n-C₃F₇—, (CF₃)₂CF— 11 11797 68 63 i-C₃F₇— 4 4 (CF₃)₂CF— (CF₃)₂CF— N/R* 115 79 68 60 5 5(CF₃)₂CFCF₂— (CF₃)₂CFCF_(2—) 41 118 103  70 63

[0135] Examining the data in TABLE 1, the high advancing water contactangles and generally high receding water contact angles are unexpectedfor a polymer containing short branched fluoroaliphatic groups. Goodadvancing and receding contact angles vs. n-hexadecane are alsoexhibited by polymers of this invention.

Examples 6-7

[0136] To determine the effect of cure temperature on the repellentperformance of polymers of this invention, advancing and recedingcontact angles against n-hexadecane and water were measured for Polymer5, the homopolymer of CH₂═CHC(O)—O—CH (CF₂CF(CF₃)₂)₂, at 25° C. (i.e.,ambient cure) and at 150° C. (i.e., forced air oven cure Again, eachpolymer was coated onto polyester film from a 3% solids polymer solutionin either C₄F₉OCH₃ or α,α,α-trifluorotoluene.

[0137] Results from these evaluations are presented in TABLE 2. TABLE 2Cure Temp. Water: n-Hexadecane: Ex. Polymer (° C.) ACA RCA ACA RCA 6 5 25 119 100 70 62 7 5 150 116 100 70 62

[0138] The data in TABLE 2 show that cure temperature has no effect onwater and hexadecane contact angles. This is believed to be due to theamorphous nature of the fluoroacrylate polymer. In contrast,conventionally used fluoroacrylate polymers having C₈F₁₇— crystallineside chains, such as homopolymers of C₈F₁₇SO₂N(CH₃)C₂H₄OC(O)OCH═CH₂(MeFOSEA) or C₈F₁₇C₂H₄OC (O)OCH═CH₂ (FOEA), require the polymer to betaken above its melt point and then cooled down to room temperature toform a highly repellent surface (i.e., a surface exhibiting a highreceding contact angle to water and n-hexadecane).

Comparative Examples C1-C7

[0139] In Comparative Examples C1-C7, various known fluorochemicalacrylate polymers outside the scope of this invention were evaluated foradvancing and receding contact angles vs. water and n-hexadecane, usingthe same procedure as described in Examples 1-5.

[0140] In Comparative Example C1, Polymer 6, the simplest secondaryalcohol-based fluorochemical acrylate polymer (i.e., where R_(f) andR_(f)′ are both CF₃—) was evaluated. In Comparative Example C2, Polymer7, a fluorochemical acrylate polymer having similar moleculararchitecture to Polymer 4, made by homopolymerizingCH₂═CHC(O)OC₂H₄OCF═C(CF(CF₃)₂)₂, was evaluated. Polymers 6 and 7 wereboth cured at ambient temperature (25° C.).

[0141] In Comparative Example C3, the fluorochemical acrylate polymer(Polymer 8) was similar to the polymers of this invention except thatR_(f)′ was a straight chain perfluorohexyl group (i.e., not the requiredbranched chain). Polymer 8 was cured at 150° C. before contact anglemeasurements were taken.

[0142] In Comparative Examples C4 and C5, Polymers 9 and 10, twocrystalline fluorochemical acrylate homopolymers containing pendantC₈F₁₇— groups, were cured at 150° C. prior to contact anglemeasurements.

[0143] In Comparative Examples C6 and C7, Polymers 11 and 12, tworelatively non-crystalline fluorochemical acrylate polymers containingC₈F₁₇-groups (made non-crystalline) by copolymerizing with n-butylacrylate or by attaching butyl pendant groups to theperfluorosulfonamido sites, respectively), were cured at 150° C. priorto contact angle measurements. In this case, only water contact anglemeasurements were taken.

[0144] Results are presented in TABLE 3. TABLE 3 Melt Point Cure Temp.Water: n-Hexadecane: Ex. Polymer (° C.) (° C.) ACA RCA ACA RCA C1  6None  25 101 81 66 56 C2  7 None  25 106 84 63 49 C3  8 N/R*  25 107 6174 58 C4  9 115 150 122 105  78 75 C5 10  80 150 125 110  80 72 C6 11None 150 120 71 N/R* N/R* C7 12 None 150 120 70 N/R* N/R*

[0145] The data in TABLE 3 show that Polymers 6, 7 and 8, cured at roomtemperature similar to the polymers of TABLE 1, generally exhibitedlower contact angles than did the polymers of this invention, indicatingthat not all amorphous fluorochemical acrylate polymers work equallywell at providing a repellent surface. The structure of theperfluoroaliphatic groups R_(f) and R_(f)′ and the moleculararchitecture associated with the perfluoroaliphatic groups must all fallwithin the range specified by this invention

[0146] Polymers 9 and 10, crystalline MeFOSEA and FOEA homopolymersrespectively, demonstrate very high advancing and receding water andhexadecane contact angles when heated to 150° C. and cooled to roomtemperature. However, they must be heated past their melt pointtemperatures of 115° C. and 80° C., respectively, to exhibit optimumrepellency.

[0147] Polymers 11 and 12, fluorochemical acrylate polymers containingC₈F₁₇ groups, are no longer crystalline, resulting in substantiallylower receding contact angles.

Examples 8-9 and Comparative Example C8

[0148] In Examples 8 and 9, Polymers 13 and 14 were compared inrepellency to the fluoropolymer in 3M FLUORAD™ FC-732 FluorochemicalCoating (Comparative Example C8), a protective coating used inelectrical applications (FC-732 is a 2% solution of a copolymer of 99/1C₇F₁₅CH₂OC(O)C(CH₃)═CH₂/CH₂═CHC(O)OH in C₄F₉OCH₃ available from 3MCompany). To run these tests, each polymer solution was diluted withC₄F₉OCH₃ to 0.2% solids solution, coupons of 6061 T-6 bare aluminum(available from Metaspec Co., San Antonio, Tex., coupon size of 1 in(2.5 cm)×1 in (2.5 cm)×0.032 in (0.8 mm), polished, with hanging hole)were dipped into each diluted polymer test solution, each wafer wasallowed to dry under ambient conditions, and advancing (Adv), static(Stat) and receding (Rec) contact angles were measured with n-hexadecaneand deionized water.

[0149] Results are presented in TABLE 4. TABLE 4 n-hexadecane, °: Water,°: Ex. Polymer Adv Rec Adv Rec 8 13 67 49 110 42 9 14 65 40 114 30 C8FC-732 71 46 109 57

[0150] The data in TABLE 4 show that the polymers of this inventionperformed similarity to the comparative fluorocopolymer containinglonger perfluoroalkyl groups.

Examples 10-15 and Comparative Examples C9-C12

[0151] This series of examples and comparative examples was run toillustrate that Polymers 15 and 16, both copolymers of this invention,are useful as surfactants in lowering the surface tension of variousliquid neat high surface energy organic materials (two differentepoxies, plasticizer, polyol) and would thus be effective in promotingthe wetting and spreading on low surface energy substrates of coatingsformulations employing such organic materials.

[0152] In Comparative Example C9, the surface tensions of the organicmaterials were measured with no surfactant added.

[0153] In Examples 10-15, the surface tensions of Polymers 15 and 16,two polymers of this invention made by copolymerizing 25% fluorochemicalmonomer with 75% PLURONIC™ L-44 diacrylate monomer and containingpendant —O—CH(CF₂CF₃)(CF(CF₃)₂) and —O—CH(CF₂CF₂CF₃)(CF(CF₃)₂) groups,respectively, were measured in the same organic materials at levels of0.1, 0.2 and 0.5 grams solids per 100 mL of material.

[0154] In Comparative Examples C10-C12, the surface tensions of Polymer17, a comparative known surfactant copolymer of similar structuralcomposition but containing pendant C₄F9— groups, were both measured inthe same organic materials at levels of 0.1, 0.2 and 0.5 grams solidsper 100 mL of solvent. The comparative copolymer was made bycopolymerizing C₄F₉SO₂N(CH₃)C₂H₄OC(O)CH═CH₂ with PLURONIC™ L-44 acrylatemonomer at a monomer weight ratio of 22/78, therefore Polymer 17contained a slightly lower fluorochemical acrylate monomer percentagethan did Polymers 15 and 16 (25/75).

[0155] Surface tension measurements in dynes/cm are presented in TABLE5. TABLE 5 Grams Surface Tension in: Ex. Polymer Polymer LG-56¹ GPE²DBP³ 6110⁴ 828⁵ C9  None 0 33 43 34 46 45 10 15 0.1 29 29 N/R* N/R* 2811 15 0.2 27 27 N/R* N/R* 28 12 15 0.5 27 24 N/R* N/R* 25 13 16 0.1 2925 24 25 22 14 16 0.2 26 24 22 24 21 15 16 0.5 26 22 22 24 20 C10 17 0.130 35 33 38 33 C11 17 0.2 28 32 32 36 29 C12 17 0.5 23 31 31 23 17

[0156] The data in TABLE 5 show that the fluorochemical acrylatepolymers of this invention generally had superior surface tensionreducing properties to the polymer containing non-degradable C₄F₉—groups.

Examples 16-18 and Example 5

[0157] Using the general procedure described for Examples 1-5, advancingand receding angle vs. water and n-hexadecane were measured for Polymers19-21, copolymers of CH₂═CHC(O)—O—CH(CF₂CF(CF₃)₂)₂ fluorochemicalacrylate monomer and vinylidene chloride having monomer ratios varyingfrom 80/20 to 95/5.

[0158] Results are presented in TABLE 6, along with contact anglemeasurements previously presented for CH₂═CHC(O)—O—CH(CF₂CF(CF₃)₂)₂homopolymer (Polymer 5) as Example 5. TABLE 6 Water: n-Hexadecane:Example Polymer % VCl₂ ACA RCA ACA RCA 16 19 20 107 79 67 44 17 20 10108 81 68 44 18 21  5 108 91 69 59  5  5  0 118 103  70 63

[0159] The data in TABLE 6 show that the amount of VCl₂ incorporated inthe copolymer generally has little effect on advancing contact angles.However, the receding contact angles do decrease fairly linearly whenthe ratio of VCl₂ in the copolymer is increased. Thus, optimum overallrepellency is realized employing a fluorochemical acrylate homopolymer.

[0160] Various modifications and alterations of this invention willbecome apparent to those skilled in the art without departing from thescope and spirit of this invention.

We claim:
 1. A compound comprising at least one unit of the formula

wherein

represents a bond in a polymerizable or a polymer chain; R_(f) is astraight chain or branched perfluoroalkyl group with five or less carbonatoms; R_(f)′ is a branched perfluoroalkyl group with three to fivecarbon atoms; R is hydrogen, methyl, fluoro or chloro; and x is atleast
 1. 2. The compound of claim 1, wherein the compound is an oligomercontaining from two to ten units of formula I.
 3. The compound of claim1, wherein the compound is a polymer containing greater than ten unitsof formula I.
 4. The compound of claim 1, wherein the compound is apolymer containing from ten to fifty units of formula I.
 5. The compoundof claim 1, wherein R_(f) is CF₃—, CF₃CF₂—, CF₃CF₂CF₂—, (CF₃)₂CF—, or(CF₃)₂CFCF₂—.
 6. The compound of claim 5, wherein R_(f) is CF₃CF₂— orCF₃CF₂CF₂—.
 7. The compound of claim 1, wherein R_(f)′ is —CF(CF₃)₂ or—CF₂CF(CF₃)₂.
 8. The compound of claim 7, wherein R_(f)′ is —CF(CF₃)₂.9. The compound of claim 1, wherein said compound is a polymer having aglass transition temperature from about 0° C. to 60° C.
 10. The compoundof claim 1, wherein said compound is a homopolymer.
 11. The compound ofclaim 1, wherein said compound is a copolymer.
 12. The compound of claim11, wherein said copolymer comprises comonomers chosen from the groupconsisting of: alkyl acrylate esters, vinyl acetate, vinylidenechloride, styrene, alkyl vinyl ethers, alkyl methacrylate esters,acrylic acid, methacrylic acid, acrylamide, methacrylamide,acrylonitrile, methacrylonitrile, polyoxyalkylene acrylate esters, andN-vinylpyrrolidone.
 13. The compound of claim 12, wherein said comonomeris an alkyl acrylate ester.
 14. A composition comprising at least oneunit of the formula

wherein,

represents a bond in a polymerizable or a polymer chain, R_(f) is astraight chain or branched perfluoroalkyl group with five or less carbonatoms, R_(f)′ is a branched perfluoroalkyl group with three to fivecarbon atoms, R is hydrogen, methyl, fluoro or chloro, and x is at least1; wherein said composition is an aqueous solution or aqueousdispersion.
 15. The composition of claim 14, wherein said composition isan aqueous dispersion.
 16. The method of claim 15, wherein said aqueousdispersion comprises from about 5 to 50 wt-% of said compound.
 17. Themethod of claim 16, wherein said aqueous dispersion comprises from about0.5 to 15 wt-% of a dispersing and/or emulsifying agent.
 18. A method oftreating a substrate to render it oil-and/or water-repellent comprisingthe step of treating the substrate with a composition according to claim14.
 19. The method of claim 18, wherein said treatment of said substrateis accomplished by immersion, flooding, spraying, padding, foaming, kissrolling, metering, or painting.
 20. A method of coating an electricaldevice comprising applying a composition according to claim
 14. 21. Amethod of coating optical fibers comprising applying a compositionaccording to claim
 14. 22. An article comprising a substrate treatedwith a composition according to claim
 14. 23. The article of claim 22,wherein said substrate is a fibrous, or a hard surface substrate. 24.The article of claim 22, wherein said substrate is an optical fiber. 25.The article of claim 22, wherein said substrate is an electrical device.26. A method of reducing the surface tension of a liquid comprisingadding a compound according to claim 1 to said liquid.
 27. The method ofclaim 26, wherein said compound is a copolymer.
 28. The method of claim27, wherein said copolymer comprises a polyoxyalkylene oxide acrylateester.